A power converter and a control method thereof

Abstract

This invention relates to the field of power electronics technology, and in particular to a power converter and its control method, comprising: a buck module and a boost module connected to each other, wherein the buck module is also connected to the voltage input terminal of the power converter, and the boost module is also connected to the voltage output terminal of the power converter; the first voltage range and the second voltage range of this invention constitute a wide input voltage range, and the duty cycle of the buck module and the boost module are different under different voltage ranges. By reasonably setting the duty cycle of the buck module and the boost module, the input voltage can be converted into a set stable voltage under a wide input voltage range, effectively solving the problem in the prior art that it is difficult to meet the stable voltage output under a wide input voltage range.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and in particular to a power converter and its control method. Background Technology

[0002] As a core component in the development of social technology, power converters require, at the technical level, reduced losses to achieve high efficiency and high power density. Currently, in many applications, there is a frequent need to convert 54V to 12V, highlighting the growing importance of this requirement. For example, in some industrial automation equipment and certain modules of communication base stations, the conversion efficiency and power density of 54V to 12V directly affect the performance, stability, and energy consumption of the equipment.

[0003] Existing power converters typically have fixed input and fixed output (e.g., fixed input 54V and fixed output 12V). However, for wide-range input voltages, it is often difficult to maintain a stable output voltage. For example, when the input voltage fluctuates between 48V and 54V, a stable 12V output can be achieved by adjusting the duty cycle of the buck power converter. However, when the input voltage is less than 48V, the duty cycle will need to be greater than 50% to maintain a stable 12V output. In this case, if it is a half-bridge circuit, it will lead to uneven current distribution between inductors Lq1 and Lq2, thus affecting the overall circuit efficiency and reducing product reliability. For a full-bridge circuit, during switching, the voltage across the combined energy storage capacitors C1 and C2 is not equal to the voltage across the input capacitor Cin, causing a current surge between the two sets of capacitors, which further reduces product efficiency and reliability.

[0004] Therefore, overcoming the shortcomings of the existing technology is an urgent problem to be solved in this technical field. Summary of the Invention

[0005] The technical problem to be solved by the present invention is how to provide a power converter that can output a stable voltage based on a wide range of input voltages.

[0006] The present invention adopts the following technical solution:

[0007] In a first aspect, a power converter is provided, comprising: a buck module and a boost module connected to each other, wherein the buck module is also connected to the voltage input terminal of the power converter, and the boost module is also connected to the voltage output terminal of the power converter;

[0008] When the input voltage is within the first voltage range, the duty cycle of the buck module is less than a preset threshold, and the duty cycle of the boost module is equal to 1. The buck module is used to reduce the input voltage to a set stable voltage, and the boost module is used to directly output the stable voltage to the output terminal of the power converter.

[0009] When the input voltage is within the second voltage range, the duty cycle of the buck module is greater than or equal to a preset threshold, and the duty cycle of the boost module is less than 1. The buck module is used to reduce the input voltage to an intermediate voltage lower than the set stable voltage, and the boost module is used to boost the intermediate voltage and output the set stable voltage, and output the stable voltage to the output terminal of the power converter.

[0010] Preferably, the step-down module includes a half-bridge structure of switching bridge, voltage divider capacitors and inductor components connected to each other; the inductor components include inductor Lq1 and inductor Lq2; the switching bridge includes switch Q1, switch Q2, switch QR1 and switch QR2; and the voltage divider capacitor includes capacitor Cb.

[0011] The switches Q2, Q1, and QR1 are connected in sequence. One end of the switch Q2 is connected to the first input terminal of the power converter, and one end of the switch QR1 is grounded.

[0012] The first node between switch Q1 and switch Q2 is connected to one end of capacitor Cb, the other end of capacitor Cb is connected to one end of inductor Lq2 and one end of switch QR2, the other end of inductor Lq2 is connected to the second output terminal of the step-down module, and the other end of switch QR2 is grounded.

[0013] The second node between switch Q1 and switch QR1 is connected to one end of inductor Lq1, and the other end of inductor Lq1 is connected to the first output terminal of the step-down module.

[0014] Preferably, the step-down module includes a full-bridge switching bridge, voltage divider capacitors, and inductor components that are interconnected; the inductor components include inductor Lq1 and inductor Lq2; the switching bridge includes switches Q3, Q4, Q5, Q6, QR3, and QR4; and the voltage divider capacitors include capacitor C1 and capacitor C2.

[0015] The switches Q3, Q4, and QR3 are connected in sequence, and the switches Q5, Q6, and QR4 are connected in sequence.

[0016] One end of switch Q3 and switch Q5 is connected to the first input terminal of the power converter, and one end of switch QR3 and switch QR4 is grounded;

[0017] The third node between switch Q5 and switch Q6 is connected to one end of capacitor C1, the other end of capacitor C1 is connected to the fourth node between switch Q4 and switch QR3, the fourth node is connected to one end of inductor Lq1, and the other end of inductor Lq1 is connected to the first output terminal of the step-down module.

[0018] The fifth node between switch Q3 and switch Q4 is connected to one end of capacitor C2, the other end of capacitor C2 is connected to the sixth node between switch Q6 and switch QR4, the sixth node is connected to one end of inductor Lq2, and the other end of inductor Lq2 is connected to the second output terminal of the step-down module.

[0019] Preferably, when the inductor assembly is a coupled inductor, the inductors Lq1 and Lq2 are wound on the same magnetic core assembly, the polarities of the inductors Lq1 and Lq2 are opposite, and the absolute value of the coupling coefficient of the inductors Lq1 and Lq2 ranges from 0 to 1.

[0020] Preferably, the boost module includes a multi-stage interconnected BOOST circuit, which includes an inductor Ls, a switch SR, and a switch S;

[0021] One end of the inductor Ls is connected to the first output terminal and / or the second output terminal of the buck module, and the other end of the inductor Ls is connected to one end of the switch SR and one end of the switch S respectively; the other end of the switch S is grounded, and the other end of the switch SR is connected to the other end of the switch SR in other stages of the BOOST circuit and the first output terminal of the power converter.

[0022] Preferably, when the two-stage BOOST circuits are connected through an intermediate interconnection, the first-stage BOOST circuit includes inductor Ls1, switch SR1 and switch S1; the second-stage BOOST circuit includes inductor Ls2, switch SR2 and switch S2.

[0023] One end of the inductor Ls2 is connected to the second output terminal of the step-down module, and the other end of the inductor Ls2 is connected to one end of the switch SR2 and one end of the switch S2 respectively; the other end of the switch S2 is grounded.

[0024] One end of the inductor Ls1 is connected to the first output terminal and the second output terminal of the step-down module, respectively. The other end of the inductor Ls1 is connected to one end of the switch SR1 and one end of the switch S1, respectively. The other end of the switch S1 is grounded. The other end of the switch SR1 is connected to the other end of the switch SR2 and the first output terminal of the power converter.

[0025] Preferably, when the two-stage BOOST circuits are connected in an isolated manner: the first-stage BOOST circuit includes inductor Ls1, switch SR1 and switch S1; the second-stage BOOST circuit includes inductor Ls2, switch SR2 and switch S2;

[0026] One end of the inductor Ls2 is connected to the second output terminal of the step-down module, and the other end of the inductor Ls2 is connected to one end of the switch SR2 and one end of the switch S2 respectively; the other end of the switch S2 is grounded.

[0027] One end of the inductor Ls1 is connected to the first output terminal of the step-down module, and the other end of the inductor Ls1 is connected to one end of the switch SR1 and one end of the switch S1 respectively; the other end of the switch S1 is grounded, and the other end of the switch SR1 is connected to the other end of the switch SR2 and the first output terminal of the power converter.

[0028] Preferably, when the switching bridge of the buck module is a half-bridge structure and the duty cycle of the buck module is greater than or equal to a preset threshold, if the buck module and the BOOST circuit have the same frequency, PWMq1 is phase-shifted by 180 degrees from PWMqr1, PWMq2 and PWMs2 respectively, PWMqr1 is phase-shifted by 180 degrees from PWMs1, PWMq2 is phase-shifted by 180 degrees from PWMqr2 and PWMs1 respectively, PWMs1 is phase-shifted by 180 degrees from PWMsr1 and PWMs2 respectively, and PWMs2 is phase-shifted by 180 degrees from PWMsr2;

[0029] If the step-down module and the BOOST circuit have different frequencies, PWMq1 is phase-shifted by 180 degrees from PWMqr1 and PWMq2 respectively, PWMq2 is phase-shifted by 180 degrees from PWMqr2, PWMs1 is phase-shifted by 180 degrees from PWMsr1 and PWMs2 respectively, and PWMs2 is phase-shifted by 180 degrees from PWMsr2; wherein, PWMq1 is the control signal of switch Q1, PWMqr1 is the control signal of switch QR1, PWMq2 is the control signal of switch Q2, PWMqr2 is the control signal of switch QR2, PWMs1 is the control signal of switch S1, PWMsr1 is the control signal of switch SR1, PWMs2 is the control signal of switch S2, and PWMsr2 is the control signal of switch SR2.

[0030] Preferably, when the switching bridge of the buck module is a full-bridge structure and the duty cycle of the buck module is greater than or equal to a preset threshold, if the buck module and the BOOST circuit have the same frequency, PWMq13 is phase-shifted by 180 degrees from PWMqr1 and PWMq24 respectively, PWMq24 is phase-shifted by 180 degrees from PWMqr2 respectively, PWMs1 is phase-shifted by 180 degrees from PWMsr1 and PWMs2 respectively, and PWMs2 is phase-shifted by 180 degrees from PWMsr2;

[0031] If the step-down module has a different frequency than the BOOST circuit, PWMq13 is phase-shifted by 180 degrees from PWMqr1 and PWMq24 respectively, PWMq24 is phase-shifted by 180 degrees from PWMqr2, PWMs1 is phase-shifted by 180 degrees from PWMsr1 and PWMs2 respectively, and PWMs2 is phase-shifted by 180 degrees from PWMsr2.

[0032] Wherein, PWMq13 is the control signal for switches Q4 and Q5, PWMqr1 is the control signal for switch QR3, PWMq24 is the control signal for switches Q3 and Q6, PWMqr2 is the control signal for switch QR4, PWMs1 is the control signal for switch S1, PWMsr1 is the control signal for switch SR1, PWMs2 is the control signal for switch S2, and PWMsr2 is the control signal for switch SR2.

[0033] In a second aspect, a control method for a power converter is provided, the control method being implemented in the power converter as described in the first aspect, comprising:

[0034] When the input voltage is within the first voltage range, the duty cycle of the buck module is less than a preset threshold, and the duty cycle of the boost module is equal to 1; the buck module reduces the input voltage to a set stable voltage, and the boost module directly outputs the stable voltage to the output terminal of the power converter;

[0035] When the input voltage is within the second voltage range, the duty cycle of the buck module is greater than or equal to a preset threshold, and the duty cycle of the boost module is less than 1. The buck module reduces the input voltage to an intermediate voltage lower than the set stable voltage, and the boost module boosts the intermediate voltage and outputs the set stable voltage, and outputs the stable voltage to the output terminal of the power converter.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0037] The first voltage range and the second voltage range of the present invention constitute a wide input voltage range. Under different voltage ranges, the duty cycle of the buck module and the boost module are also different. By reasonably setting the duty cycle of the buck module and the boost module, the input voltage can be converted into a set stable voltage under a wide input voltage range, which effectively solves the problem in the prior art that it is difficult to meet the stable voltage output for a wide range of input voltages. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the structure of a power converter provided in an embodiment of the present invention;

[0040] Figure 2 This is a schematic diagram of the structure of a step-down module provided in an embodiment of the present invention;

[0041] Figure 3 This is a schematic diagram of a half-bridge switch bridge provided in an embodiment of the present invention;

[0042] Figure 4 This is a schematic diagram of a full-bridge switch bridge provided in an embodiment of the present invention;

[0043] Figure 5 This is a schematic diagram of the structure of a coupled inductor provided in an embodiment of the present invention;

[0044] Figure 6 This is a schematic diagram of a boost module provided in an embodiment of the present invention;

[0045] Figure 7 This is a schematic diagram of a BOOST circuit provided in an embodiment of the present invention;

[0046] Figure 8 This is a schematic diagram of a two-stage interconnected boost module provided in an embodiment of the present invention;

[0047] Figure 9 This is a schematic diagram of a two-stage isolated boost module provided in an embodiment of the present invention;

[0048] Figure 10 This is a schematic diagram of an isolated three-stage BOOST circuit provided in an embodiment of the present invention;

[0049] Figure 11 It is a schematic structural diagram of an isolated four - level BOOST circuit provided by an embodiment of the present invention;

[0050] Figure 12 It is a schematic structural diagram of an isolated N - level BOOST circuit provided by an embodiment of the present invention;

[0051] Figure 13 It is a schematic structural diagram of an interconnected three - level BOOST circuit provided by an embodiment of the present invention;

[0052] Figure 14 It is a schematic structural diagram of an interconnected N - level BOOST circuit provided by an embodiment of the present invention;

[0053] Figure 15 It is a specific schematic structural diagram of a power converter provided by an embodiment of the present invention;

[0054] Figure 16 It is a PWM timing diagram of a power converter provided by an embodiment of the present invention when D1 < D1max;

[0055] Figure 17 It is a PWM timing diagram of a power converter provided by an embodiment of the present invention when D1 ≥ D1max and the buck module and the BOOST circuit have the same frequency;

[0056] Figure 18 It is a PWM timing diagram of a power converter provided by an embodiment of the present invention when D1 ≥ D1max and the buck module and the BOOST circuit have different frequencies;

[0057] Figure 19 It is a schematic structural diagram of the combination of a half - bridge buck stage and a boost module of an isolated two - level BOOST circuit provided by an embodiment of the present invention;

[0058] Figure 20 It is a schematic structural diagram of a power converter formed by the combination of a half - bridge buck module and a boost module of an isolated three - level BOOST circuit provided by an embodiment of the present invention;

[0059] Figure 21 It is a schematic structural diagram of a power converter formed by the combination of a half - bridge buck module and a boost module of an isolated four - level BOOST circuit provided by an embodiment of the present invention;

[0060] Figure 22 It is a schematic structural diagram of a power converter formed by the combination of a half - bridge buck module and a boost module of an isolated N - level BOOST circuit provided by an embodiment of the present invention;

[0061] Figure 23It is a schematic structural diagram of a power converter provided by an embodiment of the present invention, which combines a half-bridge buck module with an interconnected two-stage BOOST circuit boost module, and the inductance component is a discrete inductor;

[0062] Figure 24 It is a schematic structural diagram of a power converter provided by an embodiment of the present invention, which combines a half-bridge buck module with an interconnected two-stage BOOST circuit boost module, and the inductance component is a coupled inductor;

[0063] Figure 25 It is a schematic structural diagram of a power converter provided by an embodiment of the present invention, which combines a half-bridge buck module with an interconnected three-stage BOOST circuit boost module;

[0064] Figure 26 It is a schematic structural diagram of a power converter provided by an embodiment of the present invention, which combines a half-bridge buck module with an interconnected N-stage BOOST circuit boost module;

[0065] Figure 27 It is a schematic structural diagram of a power converter provided by an embodiment of the present invention, which combines a full-bridge buck module with an isolated two-stage BOOST circuit boost module, and the inductance component is a discrete inductor;

[0066] Figure 28 It is a PWM timing diagram of a power converter provided by an embodiment of the present invention when D1 < D1max;

[0067] Figure 29 It is a PWM timing diagram of a power converter provided by an embodiment of the present invention when D1 >= D1max and the buck circuit and the Boost are of the same frequency;

[0068] Figure 30 It is a PWM timing diagram of a power converter provided by an embodiment of the present invention when D1 >= D1max and the buck circuit and the Boost are of different frequencies;

[0069] Figure 31 It is a schematic structural diagram of a power converter provided by an embodiment of the present invention, which combines a full-bridge buck module with an isolated two-stage BOOST circuit boost module, and the inductance component is a coupled inductor;

[0070] Figure 32 It is a schematic structural diagram of a power converter provided by an embodiment of the present invention, which combines a full-bridge buck module with an isolated three-stage BOOST circuit boost module;

[0071] Figure 33 It is a schematic structural diagram of a power converter provided by an embodiment of the present invention, which combines a full-bridge buck module with an isolated four-stage BOOST circuit boost module;

[0072] Figure 34 This is a schematic diagram of the structure of a power converter combining a full-bridge buck module and an isolated N-stage BOOST circuit boost module, provided in an embodiment of the present invention.

[0073] Figure 35 This is a schematic diagram of a power converter that combines a full-bridge buck converter with an interconnected two-stage BOOST circuit boost converter, with discrete inductors as the inductor component, according to an embodiment of the present invention.

[0074] Figure 36 This is a schematic diagram of a power converter that combines a full-bridge buck converter with an interconnected two-stage BOOST circuit boost converter, with the inductor component being a coupled inductor, according to an embodiment of the present invention.

[0075] Figure 37 This is a schematic diagram of the structure of a power converter combining a full-bridge buck module and an interconnected three-stage BOOST circuit boost module, provided in an embodiment of the present invention.

[0076] Figure 38 This is a schematic diagram of the structure of a power converter combining a full-bridge buck module and an interconnected N-stage BOOST circuit boost module, provided in an embodiment of the present invention.

[0077] Figure 39 This is a flowchart illustrating a control method for a power converter provided in an embodiment of the present invention. Detailed Implementation

[0078] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0079] Unless the context otherwise requires, throughout the specification and claims, the term "comprising" is interpreted as openly inclusive, meaning "including, but not limited to." In the description of the specification, terms such as "one embodiment," "some embodiments," "exemplary embodiment," "example," "specific example," or "some examples" are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this disclosure. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics mentioned may be included in any suitable manner in any one or more embodiments or examples; that is, although they may be incorporated into embodiments or examples using the above terms for reasons such as order and position, it does not limit them to be incorporated in combination by a single embodiment or example.

[0080] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this disclosure, unless otherwise stated, "a plurality of" means two or more. Furthermore, for example, the description may use the prefix "A" or "B" to describe the same type of nouns as two independent entities. In this case, the corresponding features defined with "A" and "B" are used only to distinguish between similar entities and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features.

[0081] In describing some embodiments, the terms "coupled," "coupled," and "connected," and their derivative expressions, may be used. For example, the term "connected" may be used in describing some embodiments to indicate that two or more components have direct physical or electrical contact with each other. Similarly, the term "coupled" may be used in describing some embodiments to indicate that two or more components have direct physical or electrical contact. However, the terms "connected" or "coupled" may also refer to two or more components that do not have direct contact with each other but still cooperate or interact with each other, such as "optical coupling," "wireless connection," etc. The embodiments disclosed herein are not necessarily limited to the scope of this invention.

[0082] Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0083] Example 1:

[0084] In existing technologies, when the input voltage is between 48V and 54V, a stable 12V output can be achieved by adjusting the duty cycle of the buck converter. However, when the input voltage is less than 48V, the duty cycle must be greater than 50% to maintain a stable 12V output. In this case, if it's a half-bridge circuit, it will lead to uneven current distribution between inductors Lq1 and Lq2, affecting the overall circuit efficiency and reducing product reliability. For a full-bridge circuit, during switching, the voltage across the combined energy storage capacitors C1 and C2 is not equal to the voltage across the input capacitor Cin, causing a current surge between the two sets of capacitors, thus reducing product efficiency and reliability. Specifically: In the existing power converter technology field, the buck converter is a common voltage conversion method. When the input voltage is in the 48V-54V range, based on a specific circuit topology and control principle, it can precisely control the output voltage by adjusting the ratio of the on and off times of the internal switches, i.e., the duty cycle, thereby achieving a stable 12V output. This process relies on the basic voltage conversion formula of a buck converter: Vout = D * Vin (where Vout is the output voltage, D is the duty cycle, and Vin is the input voltage). Within this voltage range, by appropriately changing the duty cycle D, the output voltage Vout can be kept stable at 12V even when the input voltage fluctuates.

[0085] However, when the input voltage drops to the 40V-48V range, the duty cycle required to maintain a 12V output, as calculated by the above formula, will gradually increase. With a large duty cycle, components such as inductors and capacitors in the circuit will become unstable, leading to circuit instability. While a stable 12V output can be achieved, efficiency will be significantly reduced.

[0086] To address the aforementioned problems, Embodiment 1 of the present invention provides a power converter, such as... Figure 1 As shown, the device includes: a buck module and a boost module connected to each other. The buck module is also connected to the voltage input terminal of the power converter, and the boost module is also connected to the voltage output terminal of the power converter. When the input voltage is in a first voltage range, the duty cycle of the buck module is less than a preset threshold, and the duty cycle of the boost module is equal to 1. The buck module is used to reduce the input voltage to a set stable voltage, and the boost module is used to directly output the stable voltage to the output terminal of the power converter. When the input voltage is in a second voltage range, the duty cycle of the buck module is greater than or equal to the preset threshold, and the duty cycle of the boost module is less than 1. The buck module is used to reduce the input voltage to an intermediate voltage lower than the set stable voltage, and the boost module is used to boost the intermediate voltage and output the set stable voltage, and output the stable voltage to the output terminal of the power converter.

[0087] The buck module, serving as the front-end processing unit of the power converter, is directly connected to the input voltage source to perform preliminary voltage reduction on the input voltage. Internally, it typically includes key components such as power switches (e.g., MOSFETs), inductors, diodes, and capacitors. Through specific circuit connections, a buck topology is formed. Under different input voltage conditions, the input voltage is reduced by controlling the on and off times of the power switches (i.e., adjusting the duty cycle).

[0088] The boost module is located after the buck module and connected to the output of the power converter. The boost module mainly includes a boost inductor, a boost diode, a power switch, and capacitors. When the input voltage is within the second voltage range, the boost module boosts the voltage output from the buck module to ensure that the final output voltage is stable at a set value (e.g., 12V).

[0089] In one embodiment, the first voltage range is greater than the second voltage range. For example, the first voltage range may be 48V-54V, and the second voltage range may be 40V-48V.

[0090] When the input voltage is within a first voltage range, the duty cycle of the buck module is less than a preset threshold. This preset threshold is a key duty cycle value precisely calculated during circuit design and debugging based on factors such as the input voltage range, output voltage requirements, and component parameters. For example, when the input voltage is 54V, calculations show that to obtain a 12V output voltage, the duty cycle of the buck module might be set to 0.22 (this is just an example value; the actual value needs to be calculated based on specific circuit parameters). Within this first voltage range, the buck module can dynamically adjust its duty cycle based on minor fluctuations in the input voltage through a feedback control circuit, ensuring a stable output voltage of 12V. A duty cycle of 1 for the boost module means that the switch in the boost module is continuously conducting, and the boost inductor is essentially directly connected to the circuit without performing any boosting action. In this case, the voltage conversion of the entire power converter mainly relies on the buck module, while the boost module is in a direct-acting auxiliary state.

[0091] The voltage conversion process described above includes: the input voltage first enters the buck module; inside the buck module, when the switch is on, the input voltage is applied to the corresponding inductor, the inductor begins to store energy, and the current rises linearly; when the switch is off, the inductor releases energy to the capacitor and load through the diode, and the capacitor smooths the output voltage. By precisely controlling the ratio of the switch's on and off times (i.e., the duty cycle), the buck module can gradually reduce a higher input voltage (e.g., 54V) to a set stable voltage (e.g., 12V). The stable voltage is then directly transmitted to the output of the power converter through the boost module (which, due to its 1% duty cycle, acts like a wire), providing a stable power supply to the external load.

[0092] When the input voltage is within the second voltage range, the duty cycle of the buck module is greater than or equal to the preset threshold, and the duty cycle of the boost module is less than 1. A stable voltage is obtained by first bucking and then boosting the voltage.

[0093] The principle by which the boost module improves output voltage instability includes:

[0094] Regarding inductance, in a power converter combining a buck module and a boost module, when the input voltage is in the second voltage range, the buck module reduces the input voltage to an intermediate voltage lower than the set stable voltage. At this point, the ripple characteristics of the intermediate voltage output by the buck module change. Due to the addition of the boost module, the equivalent inductance characteristics of the entire circuit also change.

[0095] From an energy perspective, the inductor in the boost module also participates in energy storage and release during the switching cycle. During the boost process, the inductor stores energy when the switch is on and releases it when the switch is off, working in conjunction with the inductor in the buck module. For example, when increased inductor current ripple in the buck module causes energy fluctuations, the boost module inductor can buffer these fluctuations to some extent, smoothing the inductor current across the entire circuit through its own energy storage and release process.

[0096] From a circuit topology perspective, there is a coupling relationship between the buck and boost modules, which together form a new energy transfer path. This coupling causes the inductors to influence each other, limiting excessive changes in inductor current to some extent. For example, by properly configuring the connection method and component parameters between the two modules, the rate of change of inductor current can be constrained, thereby preventing the inductor from entering saturation.

[0097] Regarding capacitors, the operating environment changes with the involvement of the boost module. The capacitors in the boost module and the buck module together form a filter network. During the boost process, the capacitors in the boost module charge and discharge during switching operations, sharing some of the stress on the buck module capacitors.

[0098] From the perspective of voltage ripple, because the boost module participates in energy transfer, the change in charge of the buck module capacitor is reduced, thereby lowering the capacitor voltage ripple. For example, during the switching operation of the boost module, its capacitor absorbs or releases some charge, making the change in charge flowing through the buck module capacitor in the entire circuit smoother, thus reducing capacitor voltage ripple and improving the stability of the voltage across the capacitor.

[0099] The voltage conversion process described above includes: after the input voltage enters the buck module, it is stepped down to an intermediate voltage. The intermediate voltage is then transmitted to the boost module. In the boost module, when the switch is on, the intermediate voltage is applied to the boost inductor, which stores energy and the current increases. When the switch is off, the inductor, connected in series with the input voltage, releases energy to the capacitor and load through a diode. The capacitor smooths the voltage, causing the voltage to rise.

[0100] In summary, the power converter proposed in this embodiment, which combines a buck module and a boost module, breaks through the input voltage limitation of traditional buck power converters by determining the range of the input voltage and adjusting the duty cycle and operating state of the two modules accordingly. This greatly expands the applicable input voltage range of the power converter, improves its reliability and practicality in complex power supply environments, and provides a more effective solution for stable power supply of various electronic devices.

[0101] The structure of the buck module and the boost module will be described in detail below.

[0102] In one embodiment, such as Figure 2 and Figure 3 As shown, the step-down module includes a half-bridge switching bridge, voltage divider capacitors, and inductor components that are interconnected; the inductor components include inductor Lq1 and inductor Lq2; the switching bridge can be a half-bridge structure or a full-bridge structure.

[0103] When the switching bridge is a half-bridge structure, the switching bridge includes switches Q1, Q2, QR1, and QR2, and the voltage divider capacitor includes capacitor Cb. Switches Q2, Q1, and QR1 are connected in sequence. One end of switch Q2 is connected to the first input terminal of the power converter, and one end of switch QR1 is grounded. The first node between switch Q1 and switch Q2 (as shown in Figure A) is connected to one end of capacitor Cb. The other end of capacitor Cb is connected to one end of inductor Lq2 and one end of switch QR2, respectively. The other end of inductor Lq2 is connected to the second output terminal (represented by X) of the buck module, and the other end of switch QR2 is grounded. The second node between switch Q1 and switch QR1 (as shown in Figure B) is connected to one end of inductor Lq1, and the other end of inductor Lq1 is connected to the first output terminal (represented by Y) of the buck module.

[0104] When the input voltage is connected to the first input terminal of the power converter, current flows through switch Q1 into the switching bridge circuit. When the input voltage is within the first voltage range, the duty cycle of the buck module is less than a preset threshold. At this time, the current change in inductors Lq1 and Lq2 is adjusted by controlling the ratio of the on and off times (i.e., the duty cycle) of switches Q1 and Q2. During the on-time of switches Q1 and Q2, the input voltage charges inductors Lq1 and Lq2, storing energy; during the off-time of switches Q1 and Q2, the current in inductors Lq1 and Lq2 releases energy, thereby achieving an initial voltage reduction of the input voltage. Simultaneously, capacitor Cb acts as a voltage divider, working in conjunction with inductors Lq1 and Lq2 to make the output voltage more stable.

[0105] When the input voltage is within the second voltage range, the duty cycle of the buck module is greater than or equal to a preset threshold. At this time, the conduction times of switches Q1 and Q2 are relatively long, increasing the charging time of inductors Lq1 and Lq2 and thus increasing the current. However, due to the low input voltage, to avoid inductor saturation and other issues, the input voltage needs to be reduced to an intermediate voltage lower than the set stable voltage. Then, a subsequent boost module raises the intermediate voltage to the required stable voltage.

[0106] In a half-bridge structure, when the duty cycle of the switching bridge is large, the currents in inductors Lq1 and Lq2 will increase. As the duty cycle increases, the inductor current ripple also increases. Large current ripple may cause the inductor to enter saturation. Once saturated, the inductance value drops sharply, no longer meeting the inductor characteristics required for normal operation. For example, under normal conditions, an inductor can impede changes in current, making the energy storage and release process relatively stable. However, this stable energy conversion process is disrupted after saturation. This causes significant fluctuations in the intermediate voltage output of the buck module, making it impossible to provide a stable input voltage for the subsequent boost module, thus affecting the stability of the final output voltage and making it difficult to achieve a stable 12V output.

[0107] For capacitor Cb, due to the increased inductor current ripple, the capacitor needs to withstand a larger charging and discharging current. With the increased charging and discharging current, the voltage ripple across the capacitor also increases. Larger voltage ripple leads to voltage instability across the capacitor, preventing it from effectively smoothing the output voltage. This negatively impacts the stability of the output voltage, hindering a stable 12V output.

[0108] Meanwhile, when the duty cycle is large, the conduction time of switches Q1 and Q2 is relatively long. During prolonged conduction, the losses of the switching devices increase, mainly including conduction losses and switching losses. Switching losses are caused by the rapid changes in voltage and current during the switching process. These losses lead to heating of the switching devices, and their electrical parameters may change; for example, the on-resistance of the switch may increase. This further affects the circuit performance, making it difficult to maintain a stable 12V output voltage.

[0109] In one embodiment, such as Figure 4As shown, the step-down module includes an interconnected full-bridge switching bridge, voltage divider capacitors, and inductor components; the inductor components include inductor Lq1 and inductor Lq2; the switching bridge includes switches Q3, Q4, Q5, Q6, QR3, and QR4; the voltage divider capacitors include capacitors C1 and C2; switches Q3, Q4, and QR3 are connected in sequence, and switches Q5, Q6, and QR4 are connected in sequence; one end of switches Q3 and Q5 is connected to the first input terminal of the power converter, and one end of switches QR3 and QR4 is grounded; the third node between switches Q5 and Q6 (as shown by C in the figure) is connected to the... One end of capacitor C1 is connected to the fourth node (as shown in D in the figure) between switch Q4 and switch QR3. The fourth node is connected to one end of inductor Lq1, and the other end of inductor Lq1 is connected to the first output terminal (i.e., Y in the figure) of the step-down module. The fifth node (as shown in E in the figure) between switch Q3 and switch Q4 is connected to one end of capacitor C2. The other end of capacitor C2 is connected to the sixth node (as shown in F in the figure) between switch Q6 and switch QR4. The sixth node is connected to one end of inductor Lq2, and the other end of inductor Lq2 is connected to the second output terminal (i.e., X in the figure) of the step-down module.

[0110] In one embodiment, when the input voltage is connected to the first input terminal of the buck module, the current flows into the link consisting of switches Q3, Q4, and QR3, as well as the link consisting of switches Q5, Q6, and QR4. At different operating stages, the direction of the current and the charging and discharging of each component are controlled by the on and off states of each switch.

[0111] When the input voltage is within the first voltage range, the duty cycle of the buck module is less than a preset threshold. At this time, the input voltage is bucked by controlling the on / off time ratio (i.e., the duty cycle) of switches Q3, Q4, Q5, and Q6. For example, when some switches are on, the input voltage is applied to the corresponding inductors and capacitors; the inductors begin to store energy, and the capacitors charge. When these switches are off, the inductors release energy, and the capacitors also participate in maintaining voltage stability, jointly causing the output voltage to change towards the set stable voltage. During this process, capacitors C1 and C2, based on their capacitance characteristics and connection positions, perform reasonable voltage division, working in conjunction with inductors Lq1 and Lq2 to reduce voltage ripple, resulting in a more stable and expected voltage output to the first and second output terminals.

[0112] When the input voltage is within the second voltage range, the circuit will operate at a duty cycle exceeding 50% to maintain a stable output. In this case, when the switch in the step-down module is switching, the series voltage of capacitors C1 and C2 is not equal to the voltage across the input capacitor Cin. There is a situation where the series voltage of capacitors C1 and C2 is greater than the voltage across the input capacitor Cin. This voltage mismatch will cause a reverse current surge because the capacitor will try to maintain its charge when the voltage changes, thereby generating a large instantaneous current in the circuit. This reverse current surge will not only affect the stability of the circuit, but also reduce the efficiency of the power conversion circuit and generate heat, thus causing safety hazards.

[0113] Therefore, when the input voltage is in the second voltage range, the buck module first reduces the input voltage to an intermediate voltage, and then the boost module adjusts the intermediate voltage to the required stable voltage. The buck module's duty cycle is greater than or equal to a preset threshold. At this time, the conduction time of each switch is adjusted accordingly. The conduction time of switches Q3, Q4, Q5, and Q6 becomes relatively longer, increasing the charging current of inductors Lq1 and Lq2. Due to the low input voltage, the overall input voltage is reduced to an intermediate voltage lower than the set stable voltage. Subsequently, further processing with the boost module and other modules is required to obtain a stable output voltage.

[0114] In one embodiment, a lower intermediate voltage means a further increase in the duty cycle of the buck module. In this case, according to the working principle of the buck circuit, the increased duty cycle results in a longer charging time and a greater amount of charge for the capacitor. Since capacitor voltage cannot change abruptly, a larger reverse current surge occurs when the difference between the series voltage of the capacitors and the voltage across the input capacitor increases. This is because the capacitor attempts to maintain its voltage during circuit state transitions, leading to greater charge transfer and thus a larger instantaneous current.

[0115] To eliminate the aforementioned instantaneous current, one approach is to utilize the characteristics of inductors. Specifically, inductors Lq1 and Lq2 in the step-down module act as a buffer against sudden current changes in the circuit. When a reverse current surge occurs, the inductor generates a back electromotive force (EMF) to impede the rapid change in current. For example, at the instant of switch switching, the current tends to surge in the opposite direction. The inductor induces an EMF in the opposite direction to the surge current, reducing the rate of change of current and thus suppressing the amplitude of the reverse surge current, limiting it to a relatively small range and preventing excessive instantaneous current from damaging the circuit.

[0116] Secondly, it can work in conjunction with the boost module, specifically through energy transfer and collaborative operation between the boost and buck modules. The inductor (let's call it Ls) in the boost module also participates in energy storage and release during switching on and off. When a reverse current surge occurs in the buck module, the inductor in the boost module can act as a buffer. At the moment of switching, the inductor Ls in the boost module absorbs some of the energy generated by the reverse surge, balancing the energy distribution in the circuit through its own energy storage process, making the current change smoother, thereby reducing the impact of the reverse current surge on the entire circuit.

[0117] Thirdly, optimization can be achieved through control strategies, specifically including adopting appropriate control strategies, such as soft-switching technology. Soft-switching technology allows switching devices to switch under zero-voltage or zero-current conditions by controlling the turn-on and turn-off times of the switching devices. For example, during the switching process between the buck and boost modules, precise control of the PWM signal timing allows the switch to operate when the voltage or current crosses zero, significantly reducing the rate of voltage and current change during the switching process and thus lowering the possibility of reverse current surges. Simultaneously, a reasonable control strategy can also coordinate the operation between the buck and boost modules, making the energy conversion of the entire circuit smoother and more stable.

[0118] Throughout the entire buck module's operation, the switching elements in the full-bridge structure dynamically turn on and off based on the input voltage and control signals. Capacitors C1 and C2, and inductors Lq1 and Lq2 work closely together to process the input voltage from different aspects (voltage division, energy storage, or filtering, etc.). Through the coordinated work of these components, the input voltage is ultimately converted into a set stable voltage (in the first voltage range) or an intermediate voltage (in the second voltage range), and works with the boost module to output the desired stable voltage.

[0119] In one embodiment, such as Figure 5 As shown, when the inductor assembly is a coupled inductor, the inductors Lq1 and Lq2 are wound on the same magnetic core assembly, the polarities of the inductors Lq1 and Lq2 are opposite, and the absolute value of the coupling coefficient of the inductors Lq1 and Lq2 ranges from 0 to 1.

[0120] The switching on and off of the switch will cause the inductor component to be in a charging or discharging state, thereby achieving the voltage reduction function. The specific implementation principle will not be explained in detail in this embodiment.

[0121] Reference Figure 5The first terminal of inductor Lq1 has opposite polarities to the first terminal of inductor Lq2, meaning the first terminal of inductor Lq1 has the same polarity as the second terminal of inductor Lq2 (both are indicated by black dots). In one embodiment, inductors Lq1 and Lq2 can be wound on the same magnetic core assembly to form a coupled inductor. The higher the absolute value of the coupling coefficient, the tighter the magnetic coupling between the two inductors, the less magnetic flux leakage, and the higher the energy transfer efficiency. For coupled inductors, the absolute value of the coupling coefficient needs to satisfy the following relationship: when the coupling coefficient is close to 1, the magnetic coupling between the two inductors is strongest, meaning that the magnetic flux between inductors Lq1 and Lq2 almost completely passes through each other's magnetic core, thereby achieving efficient magnetic energy conversion. Coupled inductors achieve mutual coupling of magnetic flux by sharing a magnetic core, which can more effectively utilize the magnetic core material and improve energy conversion efficiency. Coupled inductors can reduce the required magnetic core material, thereby reducing volume and weight, while improving the utilization efficiency of magnetic energy.

[0122] The structure of the boost module will be described in detail below.

[0123] In one embodiment, such as Figure 6 and Figure 7 As shown, the boost module includes multiple interconnected BOOST circuits. Each BOOST circuit includes an inductor Ls, a switch SR, and a switch S. One end of the inductor Ls is connected to the first output terminal and / or the second output terminal of the buck module. The other end of the inductor Ls is connected to one end of the switch SR and one end of the switch S. The other end of the switch S is grounded. The other end of the switch SR is connected to the other ends of the switches SR in other BOOST circuits and the first output terminal of the power converter. Each BOOST circuit can boost the voltage to a certain extent. By rationally designing the parameters of each stage of the circuit, such as the inductance value, capacitance value, and switch duty cycle, fine adjustment of the boost process can be achieved. When facing different input voltages and load requirements, it can more accurately stabilize the output voltage at a stable voltage, reduce voltage fluctuations, and improve the accuracy of the output voltage.

[0124] In practical applications, the input voltage may fluctuate within the range of 40V-48V, and the load may also change. A multi-stage structure allows for flexible adjustment of the operating state of each stage of the BOOST circuit according to different operating conditions, achieving optimal boost performance. For example, when the input voltage is low or the load is heavy, the number of stages involved or the duty cycle of each stage can be adjusted to ensure stable output voltage.

[0125] The working principle of a single-stage BOOST circuit includes a charging stage and a discharging stage. The charging stage works as follows: when switch S is closed and switch SR is open, inductor Ls is charged and stores energy. At this time, the current gradually increases, and an induced electromotive force is generated across inductor Ls with the left side positive and the right side negative. Since switch S is closed, the voltage at the right end of inductor Ls is clamped at a low level. At this time, the entire voltage is applied to inductor Ls, the inductor current rises linearly, and the energy stored in inductor Ls increases.

[0126] The working process of the discharge stage is as follows: When switch S is open and switch SR is closed, the induced electromotive force generated by inductor Ls becomes negative on the left and positive on the right. After being superimposed with the voltage from the step-down module, it supplies power to the load and the subsequent BOOST circuit through switch SR, releasing the energy stored in inductor Ls to the output terminal, thereby increasing the output voltage.

[0127] By cascading multiple stages of boost circuits, the boosted voltage output from the previous stage becomes the input to the next stage. After multiple boost stages, the final stable voltage is obtained at the output of the power converter. The boost process is similar for each stage, but as the number of stages increases, the output voltage gradually increases, thus achieving the conversion from an intermediate voltage to a stable 12V output voltage.

[0128] By setting up a multi-stage BOOST circuit, the intermediate voltage output from the buck module can be effectively boosted to a set stable voltage when the input voltage is within the second voltage range. This ensures stable output of the power converter over a wide input voltage range, improving system reliability and adaptability. The number of stages and parameters of the BOOST circuit can be flexibly adjusted according to actual needs to meet different boost requirements and load characteristics, exhibiting good scalability and versatility.

[0129] Multi-stage boost circuits can be connected using either intermediate interconnection or intermediate isolation. The following section explains the intermediate interconnection and isolation connection methods for two-stage boost circuits.

[0130] In one embodiment, such as Figure 8As shown, when the two-stage BOOST circuits are connected via an intermediate interconnect, the first-stage BOOST circuit includes an inductor Ls1, a switch SR1, and a switch S1; the second-stage BOOST circuit includes an inductor Ls2, a switch SR2, and a switch S2; one end of the inductor Ls2 is connected to the second output terminal of the buck module, and the other end of the inductor Ls2 is connected to one end of the switch SR2 and one end of the switch S2; the other end of the switch S2 is grounded; one end of the inductor Ls1 is connected to the first output terminal and the second output terminal of the buck module, and the other end of the inductor Ls1 is connected to one end of the switch SR1 and one end of the switch S1; the other end of the switch S1 is grounded, and the other end of the switch SR1 is connected to the other end of the switch SR2 and the first output terminal of the power converter.

[0131] In the intermediate interconnection method, one end of the inductor Ls1 in the first-stage BOOST circuit is connected to both the first and second output terminals of the buck module, allowing it to draw energy from both output terminals. Similarly, the inductor Ls2 in the second-stage BOOST circuit can also draw energy from both output terminals. The other ends of the switches SR1 and SR2 in the two-stage BOOST circuits are directly connected to the first output terminal of the power converter, achieving an interconnected structure.

[0132] During the charging phase, when switches SR1 and SR2 are closed and switches S1 and S2 are open, the voltage from the buck module flows through inductors Ls1 and Ls2, causing the current to rise linearly, and the inductors store energy. During the discharging phase, when switches SR1 and SR2 are open and switches S1 and S2 are closed, the current in inductors Ls1 and Ls2 cannot change abruptly, generating an induced electromotive force that, when superimposed on the input voltage, charges the capacitor and supplies power to the load. This interconnection method makes the energy interaction between the two circuit stages more direct and tighter, which can improve energy transfer efficiency and reduce energy loss to a certain extent.

[0133] In one embodiment, such as Figure 9As shown, when the two-stage BOOST circuits are connected via intermediate isolation: the first-stage BOOST circuit includes inductor Ls1, switch SR1, and switch S1; the second-stage BOOST circuit includes inductor Ls2, switch SR2, and switch S2; one end of inductor Ls2 is connected to the second output terminal of the buck module, and the other end of inductor Ls2 is connected to one end of switch SR2 and one end of switch S2 respectively; the other end of switch S2 is grounded; one end of inductor Ls1 is connected to the first output terminal of the buck module, and the other end of inductor Ls1 is connected to one end of switch SR1 and one end of switch S1 respectively; the other end of switch S1 is grounded, and the other end of switch SR1 is connected to the other end of switch SR2 and the first output terminal of the power converter.

[0134] In the intermediate isolation method, the inductor Ls1 of the first-stage BOOST circuit is connected to the first output terminal of the buck module, and the inductor Ls2 of the second-stage BOOST circuit is connected to the second output terminal of the buck module. Isolation is achieved between the two stages of the circuit through the connection between the inductor and the buck module. The other ends of switches SR1 and SR2 are connected to the first output terminal of the power converter.

[0135] During the charging phase, switches SR1 and SR2 are closed, and switches S1 and S2 are open. Inductors Ls1 and Ls2 independently obtain and store energy from different output terminals of the buck module. During the discharging phase, switches SR1 and SR2 are open, and switches S1 and S2 are closed. Inductors Ls1 and Ls2 each generate an induced electromotive force, which, when superimposed with the input voltage, charges the capacitor and supplies power to the load. The advantage of this isolation method is that it reduces mutual interference between the two circuit stages, improving circuit stability and reliability. When a fault or parameter fluctuation occurs in one stage of the circuit, the relatively independent connection between the inductors and the buck module has a relatively small impact on the other stage, facilitating fault diagnosis and system maintenance.

[0136] In one embodiment, such as Figure 10 for Figure 6 The diagram shows the structure of the isolated three-stage BOOST circuit in the boost module. Figure 11 for Figure 6 The diagram shows the structure of the isolated four-stage BOOST circuit in the boost module. Figure 12 for Figure 6 The diagram shows the structure of the isolated N-stage BOOST circuit in the boost module. Figure 13 for Figure 6 The diagram shows the structure of the interconnected three-stage BOOST circuit in the boost module. Figure 14 Displayed as Figure 6 The diagram shows the structure of the interconnected N-stage BOOST circuit in the boost module.

[0137] That is, for the intermediate interconnection method, one end of the inductor Lsn (n represents the stage) of the BOOST circuit of all stages is connected to the first output terminal and the second output terminal of the buck module.

[0138] In the intermediate isolation method, one end of the inductor Lsn (where n represents the stage) of one part of the BOOST circuit is connected to the first output terminal of the buck module, and one end of the inductor Lsn (where n represents the stage) of the other part of the BOOST circuit is connected to the second output terminal.

[0139] In one embodiment, Figures 10 to 14 The specific working principle of the structure shown can be derived from the simple derivation above, and will not be repeated in this embodiment.

[0140] In one embodiment, such as Figure 15 As shown, the power converter further includes an inductor Lin, a capacitor Cin, a capacitor Cout, and a resistor Rload; one end of the inductor Lin is connected to the first input terminal of the power converter, and the other end of the inductor Lin is connected to one end of the capacitor Cin and the other end of the switch Q1; the other end of the capacitor Cin is grounded; one end of the capacitor Cout is connected to the first output terminal of the power converter, and the other end of the capacitor Cout is grounded; one end of the resistor Rload is connected to the first output terminal of the power converter, and the other end of the resistor Rload is grounded.

[0141] In this embodiment, the first voltage range and the second voltage range constitute a wide input voltage range. Under different voltage ranges, the duty cycle of the buck module and the boost module are also different. By reasonably setting the duty cycle of the buck module and the boost module, the input voltage can be converted into a set stable voltage under a wide input voltage range, which effectively solves the problem in the prior art that it is difficult to meet the stable voltage output for a wide range of input voltages.

[0142] Example 2:

[0143] This embodiment will further illustrate the power converter described in Embodiment 1. This embodiment will propose some combinations of buck and boost modules to further explain the power converter.

[0144] In one embodiment, such as Figure 15 for Figure 1 The circuit structure diagram of a specific embodiment of the power converter shown is as follows: the switching bridge of the buck module is a half-bridge structure, the boost module is an isolated two-stage BOOST circuit, and the inductor component is a discrete inductor.

[0145] by Figure 15 Taking the circuit diagram as an example, when the input voltage is within the first voltage range, the duty cycle of the step-down module is less than a preset threshold. Figure 16 The pulse width modulation (PWM) timing diagram shown controls the on / off state of each switch.

[0146] When the input voltage is within the second voltage range, the duty cycle of the buck module is greater than or equal to a preset threshold. Therefore, the corresponding PWM timing diagram needs to be determined based on the frequencies of the buck and boost modules. Specifically, when the buck and boost modules operate at the same frequency, according to... Figure 17 The PWM timing diagram shown controls the on / off state of each switch; when the buck module and boost module operate at different frequencies, according to... Figure 18 The PWM timing diagram shown controls the on / off state of each switch. Here, "the buck module and the BOOST circuit have the same frequency" means that the switching frequency of the switches in the buck module is the same as the switching frequency of the switches in the subsequent BOOST circuit; "the buck module and the BOOST circuit have different frequencies" means that the switching frequency of the switches in the buck module is different from the switching frequency of the switches in the subsequent BOOST circuit.

[0147] exist Figures 16-18 In this context, D1 represents the duty cycle of the step-down module, and D1max represents the preset threshold.

[0148] exist Figure 16 In the shown PWM timing diagram, PWMq1 is phase-shifted by 180 degrees from PWMqr1 and PWMq2, PWMq2 is phase-shifted by 180 degrees from PWMqr2, PWMs1 and PWMs2 remain normally off, and PWMsr1 and PWMsr2 remain normally on. Among these, in... Figure 16 In this process, a switching cycle Ts1 is divided into several smaller time intervals, including: t0-t1, t1-t2, t2-t3, t3-t4, t4-t5, t5-t6, t6-t7, and t7-t8.

[0149] During the time period t0-t1, switches Q1, QR2, SR1, and SR2 are in the ON state; switches QR1, Q2, S1, and S2 are in the OFF state.

[0150] During the time period t1-t2, switches QR2, SR1, and SR2 are in the ON state; switches Q1, QR1, Q2, S1, and S2 are in the OFF state.

[0151] During the time period t2-t3, switches QR1, QR2, SR1, and SR2 are in the ON state; switches Q1, Q2, S1, and S2 are in the OFF state.

[0152] During the time period t3-t4, switches QR1, SR1, and SR2 are in the ON state; switches Q1, Q2, QR2, S1, and S2 are in the OFF state.

[0153] During the time period t4-t5, switches QR1, Q2, SR1, and SR2 are in the ON state; switches Q1, QR2, S1, and S2 are in the OFF state.

[0154] During the time period t5-t6, switches QR1, SR1, and SR2 are in the ON state; switches Q1, Q2, QR2, S1, and S2 are in the OFF state.

[0155] During the time period t6-t7, switches QR1, QR2, SR1, and SR2 are in the ON state; switches Q1, Q2, S1, and S2 are in the OFF state.

[0156] During the time period t7-t8, switches QR2, SR1, and SR2 are in the ON state; switches Q1, QR1, Q2, S1, and S2 are in the OFF state.

[0157] In one embodiment, such as Figure 17 As shown, when the switching bridge of the buck module is a half-bridge structure and the duty cycle of the buck module is greater than or equal to a preset threshold, if the buck module and the BOOST circuit are at the same frequency, PWMq1 is phase-shifted by 180 degrees from PWMqr1, PWMq2, and PWMs2 respectively; PWMqr1 is phase-shifted by 180 degrees from PWMs1; PWMq2 is phase-shifted by 180 degrees from PWMqr2 and PWMs1 respectively; PWMs1 is phase-shifted by 180 degrees from PWMsr1 and PWMs2 respectively; and PWMs2 is phase-shifted by 180 degrees from PWMsr2. Here, D2 refers to the duty cycle of the switching transistor in the BOOST circuit when the buck module and the BOOST circuit are at the same frequency, which will not be elaborated further below.

[0158] In one embodiment, such as Figure 18As shown, if the buck module and the BOOST circuit have different frequencies, PWMq1 is phase-shifted by 180 degrees from PWMqr1 and PWMq2 respectively, PWMq2 is phase-shifted by 180 degrees from PWMqr2, PWMs1 is phase-shifted by 180 degrees from PWMsr1 and PWMs2 respectively, and PWMs2 is phase-shifted by 180 degrees from PWMsr2; D3 refers to the duty cycle of the switching transistor in the BOOST circuit when the buck module and the BOOST circuit have different frequencies. Ts2 represents the switching period of the switching transistor in the BOOST circuit when the buck module and the BOOST circuit have different frequencies, which will not be elaborated further below.

[0159] Wherein, PWMq1 is the control signal for switch Q1, PWMqr1 is the control signal for switch QR1, PWMq2 is the control signal for switch Q2, PWMqr2 is the control signal for switch QR2, PWMs1 is the control signal for switch S1, PWMsr1 is the control signal for switch SR1, PWMs2 is the control signal for switch S2, and PWMsr2 is the control signal for switch SR2.

[0160] Figure 17 The PWM timing diagram shown is Figure 18 Please refer to the attached diagram for the specific PWM timing diagram shown.

[0161] It is worth noting that, in Figure 16 , Figure 17 and Figure 18 In this circuit, to prevent simultaneous conduction of switches when switching switches are in the ON state, a first dead time Td1, a second dead time Td2, a third dead time Td3, and a fourth dead time Td4 are set to allow for idle time. The values ​​of the first dead time Td1, Td2, Td3, and Td4 can be obtained empirically, and can also be set according to different circuit operating frequencies, different switch models, and other conditions. More specific details will not be elaborated in this embodiment.

[0162] In one embodiment, after obtaining the first dead time Td1, the second dead time Td2, the third dead time Td3, and the fourth dead time Td4, the duty cycle and switching cycle of the buck module are determined respectively, and the corresponding timing control diagram can be obtained.

[0163] Figures 19-26 The circuit diagrams show the combination of a half-bridge buck converter with different boost converters.

[0164] Figure 19 It combines a half-bridge buck converter with an isolated two-stage boost circuit, and the inductor component is a coupled inductor. Figure 20 It combines a half-bridge buck converter with an isolated three-stage boost circuit. Figure 21 It combines a half-bridge buck converter with an isolated four-stage boost circuit. Figure 22 It combines a half-bridge buck converter with an isolated N-stage BOOST circuit boost converter. Figure 23 It combines a half-bridge buck converter with an interconnected two-stage BOOST circuit boost converter, and the inductor component is a discrete inductor. Figure 24 It combines a half-bridge buck converter with an interconnected two-stage BOOST circuit boost converter, and the inductor component is a coupled inductor. Figure 25 It combines a half-bridge buck converter with an interconnected three-stage BOOST circuit boost converter. Figure 26 It combines a half-bridge buck converter with an interconnected N-level BOOST circuit boost converter.

[0165] The specific working principle of the above structure can be simply derived from Example 1, and will not be explained in detail in this example.

[0166] Example 3:

[0167] This embodiment will further illustrate the power converter described in Embodiment 1. This embodiment will propose some combinations of buck and boost modules to further explain the power converter.

[0168] In one embodiment, such as Figure 27 for Figure 1 The diagram shows a specific embodiment of the power converter circuit structure. The buck converter's switching bridge is a full-bridge structure, the boost converter is an isolated two-stage BOOST circuit, and the inductors are discrete inductors. The second terminals of inductors Lq1 and Lq2 in the full-bridge buck converter are electrically connected to the first terminals of inductors Ls1 and Ls2 in the isolated two-stage BOOST circuit boost converter, respectively.

[0169] by Figure 27 Taking the circuit diagram as an example, when the input voltage is within the first voltage range, the duty cycle of the step-down module is less than a preset threshold. Figure 28 The PWM timing diagram shown controls the on / off state of each switch.

[0170] When the input voltage is within the second voltage range, the duty cycle of the buck module is greater than or equal to a preset threshold. Therefore, the corresponding PWM timing diagram needs to be determined based on the frequencies of the buck and boost modules. Specifically, when the buck and boost modules operate at the same frequency, according to... Figure 29 The PWM timing diagram shown controls the on / off state of each switch; when the buck module and boost module operate at different frequencies, according to... Figure 30 The PWM timing diagram shown controls the on / off state of each switch.

[0171] exist Figures 28-30Among them, D1 is the duty cycle of the buck module, and D1max is the preset threshold.

[0172] Figure 28 is Figure 27 The PWM timing diagram of the power converter shown when D1 < D1max. Among them, PWMq13 is phase-shifted 180 degrees from PWMqr1 and PWMq24 respectively, PWMq24 is phase-shifted 180 degrees from PWMqr2, PWMs1 and PWMs2 are kept in the off state, and PWMsr1 and PWMsr2 are kept in the on state.

[0173] In one embodiment, as Figure 29 shown, when the switch bridge of the buck module is a full-bridge structure and the duty cycle of the buck module is greater than or equal to the preset threshold, if the buck module and the BOOST circuit have the same frequency, PWMq13 is phase-shifted 180 degrees from PWMqr1 and PWMq24 respectively, PWMq24 is phase-shifted 180 degrees from PWMqr2 respectively, PWMs1 is phase-shifted 180 degrees from PWMsr1 and PWMs2 respectively, and PWMs2 is phase-shifted 180 degrees from PWMsr2;

[0174] In one embodiment, as Figure 30 shown, if the buck module and the BOOST circuit have different frequencies, PWMq13 is phase-shifted 180 degrees from PWMqr1 and PWMq24 respectively, PWMq24 is phase-shifted 180 degrees from PWMqr2, PWMs1 is phase-shifted 180 degrees from PWMsr1 and PWMs2 respectively, and PWMs2 is phase-shifted 180 degrees from PWMsr2;

[0175] Among them, PWMq13 is the control signal of switch Q4 and switch Q5, PWMqr1 is the control signal of switch QR3, PWMq24 is the control signal of switch Q3 and switch Q6, PWMqr2 is the control signal of switch QR4, PWMs1 is the control signal of switch S1, PWMsr1 is the control signal of switch SR1, PWMs2 is the control signal of switch S2, and PWMsr2 is the control signal of switch SR2.

[0176] Figures 31-38 Shows the circuit diagram after the full-bridge buck module is combined with different boost modules.

[0177] Figure 31 is the combination of the full-bridge buck module and the isolated two-stage BOOST circuit boost module, and the inductor component is a coupled inductor. Figure 32 is the combination of the full-bridge buck module and the isolated three-stage BOOST circuit boost module. Figure 33 is the combination of the full-bridge buck module and the isolated four-stage BOOST circuit boost module. Figure 34It combines a full-bridge buck converter with an isolated N-level BOOST circuit boost converter. Figure 35 It combines a full-bridge buck converter with an interconnected two-stage BOOST circuit boost converter, and the inductor components are discrete inductors. Figure 36 It combines a full-bridge buck converter with an interconnected two-stage BOOST circuit boost converter, and the inductor component is a coupled inductor. Figure 37 It combines a full-bridge buck converter with an interconnected three-stage BOOST circuit boost converter. Figure 38 It combines a full-bridge buck converter with an interconnected N-level BOOST circuit boost converter.

[0178] The specific working principle of the above structure can be simply derived from Example 1, and will not be explained in detail in this example.

[0179] Example 4:

[0180] In Example 1, a power converter was proposed. In this example, a control method for the power converter will be proposed, such as... Figure 39 As shown, it includes:

[0181] Step 101: When the input voltage is within the first voltage range, the duty cycle of the buck module is less than the preset threshold, and the duty cycle of the boost module is equal to 1; the buck module reduces the input voltage to the set stable voltage, and the boost module directly outputs the stable voltage to the output terminal of the power converter.

[0182] When the input voltage is within a first voltage range (assuming it's a specific range above 48V), the duty cycle of the buck module is less than a preset threshold. This preset threshold is a key duty cycle value precisely calculated during circuit design and debugging based on factors such as the input voltage range, output voltage requirements, and component parameters. For example, when the input voltage is 54V, calculations show that to obtain a 12V output voltage, the buck module's duty cycle might be set to 0.22 (this is just an example value; actual values ​​need to be calculated based on specific circuit parameters). Within this first voltage range, the buck module can dynamically adjust its duty cycle based on minor fluctuations in the input voltage through a feedback control circuit, ensuring a stable output voltage of 12V. A duty cycle of 1 for the boost module means that the power switch in the boost module is continuously conducting, and the boost inductor is essentially directly connected in the circuit without performing any boosting action. In this case, the voltage conversion of the entire power converter mainly relies on the buck module, while the boost module is in a shoot-through auxiliary state.

[0183] Step 102: When the input voltage is in the second voltage range, the duty cycle of the buck module is greater than or equal to the preset threshold, and the duty cycle of the boost module is less than 1; the buck module reduces the input voltage to an intermediate voltage lower than the set stable voltage, the boost module boosts the intermediate voltage and outputs the set stable voltage, and outputs the stable voltage to the output terminal of the power converter.

[0184] When the input voltage is in the second voltage range (40V-48V), the duty cycle of the buck module is greater than or equal to a preset threshold. Since the input voltage drops to this range, according to the buck conversion formula, maintaining a 12V output would require a duty cycle exceeding the effective adjustment range of the buck module operating alone. For example, when the input voltage is 40V, relying solely on the buck module might require a duty cycle of 1.2 (which is unrealistic, as the maximum duty cycle is 1) to achieve a 12V output. Therefore, the buck module's duty cycle is adjusted to be close to or equal to its maximum value (usually close to 1), but this does not directly produce a 12V output; instead, an intermediate voltage is obtained.

[0185] When the duty cycle of the boost module is less than 1, the boost module begins to operate. Its duty cycle is calculated using a specific control algorithm based on the input voltage and the desired final output voltage (12V). For example, when the buck module steps down the 40V input voltage to an 8V intermediate voltage, the boost module calculates a suitable duty cycle of approximately 0.33 (this is just an example value; actual calculations are more precise) based on the boost formula of the BOOST circuit: Vout = Vin / (1-D) (where Vin is the input voltage of the boost module, i.e., the intermediate voltage of the buck module, 8V, and Vout is the desired final output voltage, 12V). Then, by controlling the power switching transistor in the boost module to turn on and off according to this duty cycle, the intermediate voltage is boosted.

[0186] In one embodiment, when the voltage reaches the highest value of the second voltage range (typically 48V), the duty cycle of the buck module is fixed at a maximum of 50% or slightly below 50%. At this point, if the input voltage decreases further, the output of the buck circuit loses its voltage regulation function due to the fixed duty cycle and will decrease as the input voltage decreases. In this case, the boost module is used to raise the output voltage of the first stage to the desired stable output voltage.

[0187] For the specific structure of the power converter, please refer to Embodiment 1, which will not be repeated in this embodiment.

[0188] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A power converter, characterized in that, include: A buck converter and a boost converter are interconnected, wherein the buck converter is also connected to the voltage input terminal of the power converter, and the boost converter is also connected to the voltage output terminal of the power converter; When the input voltage is within the first voltage range, the duty cycle of the buck module is less than a preset threshold, and the duty cycle of the boost module is equal to 1. The buck module is used to reduce the input voltage to a set stable voltage, and the boost module is used to directly output the stable voltage to the output terminal of the power converter. When the input voltage is within the second voltage range, the duty cycle of the buck module is greater than or equal to a preset threshold, and the duty cycle of the boost module is less than 1. The buck module is used to reduce the input voltage to an intermediate voltage lower than the set stable voltage, and the boost module is used to boost the intermediate voltage and output the set stable voltage, and output the stable voltage to the output terminal of the power converter.

2. The power converter according to claim 1, characterized in that, The step-down module includes a half-bridge structure of switching bridge, voltage divider capacitors and inductor components connected to each other; the inductor components include inductor Lq1 and inductor Lq2; the switching bridge includes switch Q1, switch Q2, switch QR1 and switch QR2; and the voltage divider capacitor includes capacitor Cb. The switches Q2, Q1, and QR1 are connected in sequence. One end of the switch Q2 is connected to the first input terminal of the power converter, and one end of the switch QR1 is grounded. The first node between switch Q1 and switch Q2 is connected to one end of capacitor Cb, the other end of capacitor Cb is connected to one end of inductor Lq2 and one end of switch QR2, the other end of inductor Lq2 is connected to the second output terminal of the step-down module, and the other end of switch QR2 is grounded. The second node between switch Q1 and switch QR1 is connected to one end of inductor Lq1, and the other end of inductor Lq1 is connected to the first output terminal of the step-down module.

3. The power converter according to claim 1, characterized in that, The step-down module includes an interconnected full-bridge switching bridge, voltage divider capacitors, and inductor components; the inductor components include inductor Lq1 and inductor Lq2; the switching bridge includes switches Q3, Q4, Q5, Q6, QR3, and QR4; and the voltage divider capacitors include capacitor C1 and capacitor C2. The switches Q3, Q4, and QR3 are connected in sequence, and the switches Q5, Q6, and QR4 are connected in sequence. One end of switch Q3 and switch Q5 is connected to the first input terminal of the power converter, and one end of switch QR3 and switch QR4 is grounded; The third node between switch Q5 and switch Q6 is connected to one end of capacitor C1, the other end of capacitor C1 is connected to the fourth node between switch Q4 and switch QR3, the fourth node is connected to one end of inductor Lq1, and the other end of inductor Lq1 is connected to the first output terminal of the step-down module. The fifth node between switch Q3 and switch Q4 is connected to one end of capacitor C2, the other end of capacitor C2 is connected to the sixth node between switch Q6 and switch QR4, the sixth node is connected to one end of inductor Lq2, and the other end of inductor Lq2 is connected to the second output terminal of the step-down module.

4. The power converter according to claim 2 or 3, characterized in that, When the inductor assembly is a coupled inductor, the inductors Lq1 and Lq2 are wound on the same magnetic core assembly, the polarities of the inductors Lq1 and Lq2 are opposite, and the absolute value of the coupling coefficient of the inductors Lq1 and Lq2 ranges from 0 to 1.

5. The power converter according to claim 2 or 3, characterized in that, The boost module includes a multi-stage interconnected BOOST circuit, which includes an inductor Ls, a switch SR, and a switch S. One end of the inductor Ls is connected to the first output terminal and / or the second output terminal of the buck module, and the other end of the inductor Ls is connected to one end of the switch SR and one end of the switch S respectively; the other end of the switch S is grounded, and the other end of the switch SR is connected to the other end of the switch SR in other stages of the BOOST circuit and the first output terminal of the power converter.

6. The power converter according to claim 5, characterized in that, When the two-stage BOOST circuits are connected through an intermediate interconnection, the first-stage BOOST circuit includes inductor Ls1, switch SR1 and switch S1; the second-stage BOOST circuit includes inductor Ls2, switch SR2 and switch S2. One end of the inductor Ls2 is connected to the second output terminal of the step-down module, and the other end of the inductor Ls2 is connected to one end of the switch SR2 and one end of the switch S2 respectively; the other end of the switch S2 is grounded. One end of the inductor Ls1 is connected to the first output terminal and the second output terminal of the step-down module, respectively. The other end of the inductor Ls1 is connected to one end of the switch SR1 and one end of the switch S1, respectively. The other end of the switch S1 is grounded. The other end of the switch SR1 is connected to the other end of the switch SR2 and the first output terminal of the power converter.

7. The power converter according to claim 5, characterized in that, When the two-stage BOOST circuits are connected in an isolated manner: the first-stage BOOST circuit includes inductor Ls1, switch SR1 and switch S1; the second-stage BOOST circuit includes inductor Ls2, switch SR2 and switch S2. One end of the inductor Ls2 is connected to the second output terminal of the step-down module, and the other end of the inductor Ls2 is connected to one end of the switch SR2 and one end of the switch S2 respectively; the other end of the switch S2 is grounded. One end of the inductor Ls1 is connected to the first output terminal of the step-down module, and the other end of the inductor Ls1 is connected to one end of the switch SR1 and one end of the switch S1 respectively; the other end of the switch S1 is grounded, and the other end of the switch SR1 is connected to the other end of the switch SR2 and the first output terminal of the power converter.

8. The power converter according to claim 7, characterized in that, When the switching bridge of the buck module is a half-bridge structure and the duty cycle of the buck module is greater than or equal to a preset threshold, if the buck module and the BOOST circuit have the same frequency, PWMq1 is phase-shifted by 180 degrees with PWMqr1, PWMq2 and PWMs2 respectively, PWMqr1 is phase-shifted by 180 degrees with PWMs1 respectively, PWMq2 is phase-shifted by 180 degrees with PWMqr2 and PWMs1 respectively, PWMs1 is phase-shifted by 180 degrees with PWMsr1 and PWMs2 respectively, and PWMs2 is phase-shifted by 180 degrees with PWMsr2. If the step-down module and the BOOST circuit have different frequencies, PWMq1 is phase-shifted by 180 degrees from PWMqr1 and PWMq2 respectively, PWMq2 is phase-shifted by 180 degrees from PWMqr2 respectively, PWMs1 is phase-shifted by 180 degrees from PWMsr1 and PWMs2 respectively, and PWMs2 is phase-shifted by 180 degrees from PWMsr2. Wherein, PWMq1 is the control signal for switch Q1, PWMqr1 is the control signal for switch QR1, PWMq2 is the control signal for switch Q2, PWMqr2 is the control signal for switch QR2, PWMs1 is the control signal for switch S1, PWMsr1 is the control signal for switch SR1, PWMs2 is the control signal for switch S2, and PWMsr2 is the control signal for switch SR2.

9. The power converter according to claim 7, characterized in that, When the switching bridge of the buck module is a full-bridge structure and the duty cycle of the buck module is greater than or equal to a preset threshold, if the buck module and the BOOST circuit have the same frequency, PWMq13 is phase-shifted by 180 degrees from PWMqr1 and PWMq24 respectively, PWMq24 is phase-shifted by 180 degrees from PWMqr2 respectively, PWMs1 is phase-shifted by 180 degrees from PWMsr1 and PWMs2 respectively, and PWMs2 is phase-shifted by 180 degrees from PWMsr2; If the step-down module has a different frequency than the BOOST circuit, PWMq13 is phase-shifted by 180 degrees from PWMqr1 and PWMq24 respectively, PWMq24 is phase-shifted by 180 degrees from PWMqr2, PWMs1 is phase-shifted by 180 degrees from PWMsr1 and PWMs2 respectively, and PWMs2 is phase-shifted by 180 degrees from PWMsr2. Wherein, PWMq13 is the control signal for switches Q4 and Q5, PWMqr1 is the control signal for switch QR3, PWMq24 is the control signal for switches Q3 and Q6, PWMqr2 is the control signal for switch QR4, PWMs1 is the control signal for switch S1, PWMsr1 is the control signal for switch SR1, PWMs2 is the control signal for switch S2, and PWMsr2 is the control signal for switch SR2.

10. A control method for a power converter, characterized in that, The control method is implemented in the power converter as described in any one of claims 1-9, comprising: When the input voltage is within the first voltage range, the duty cycle of the buck module is less than a preset threshold, and the duty cycle of the boost module is equal to 1; the buck module reduces the input voltage to a set stable voltage, and the boost module directly outputs the stable voltage to the output terminal of the power converter; When the input voltage is within the second voltage range, the duty cycle of the buck module is greater than or equal to a preset threshold, and the duty cycle of the boost module is less than 1. The buck module reduces the input voltage to an intermediate voltage lower than the set stable voltage, and the boost module boosts the intermediate voltage and outputs the set stable voltage, and outputs the stable voltage to the output terminal of the power converter.

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